A group of countries, which have pledged support to a Gulf-sponsored initiative for Yemen, said on Saturday that the Iran-backed Houthi militia and allied forces are hindering peace in the crisis-hit country.

The group, often referred to as G18, is made up of ambassadors hailing from the Gulf Cooperation Council (GCC) countries, permanent Security Council members, in addition to Germany, the Netherlands, Turkey, Japan and Egypt.

The G18 backs the GCC Initiative for Yemen, which was signed in 2011 to help extricate Yemen from its post-Arab Spring crisis by peacefully transferring power from the country’s long-time President Ali Abdullah Saleh to his former vice President Abed Rabbu Mansour Hadi.

“Unconstitutional and unilateral actions” by Houthi militias and their allied forces belonging to the deposed president Saleh are “making the search for a peaceful solution more difficult,” the G18 said in a statement.

The Yemeni capital Sanaa has been under Houthi control after the internationally recognized President Hadi was forced into exile in September 2014.

After the failed peace talks in Kuwait between Yemen’s warring sides, the Houthis and their allies in Saleh’s General People’s Congress party signed an agreement in late July to set up a council to run the country, disregarding Hadi’s government.

The ambassadors also said such actions are increasing “the divisions in Yemen and will not address the political, economic, and security problems” which has plunged the country into what the UN warned as a serious humanitarian crisis.

“We also express our concern about the escalation of violence and reiterate our call to all parties to immediately implement the cessation of hostilities,” the statement said.

It also called on all parties involved in the conflict to adhere to the UN Security Council Resolution 2216 which stipulates the withdrawal of armed groups from all cities.

The statement comes in the wake of the Saudi-led Arab Coalition resuming its Operation Restoring Hope military campaign in early August against the Houthis and Saleh forces after UN-sponsored peace talks ended without a breakthrough.